Voltage regulator



y 1951 v P. M. e. TOULON 2,555,015 7 VOLTAGE REGULATOR Filed May 16, 1949 UUU u TI M E INVENTOR- PIERRE MARIE GABRIEL TOULON- ATTORNEY p H m [1 (\n W N/W HUUH Patented May 29, 1951 2,555,015 VOLTAGE REGULATOR Pierre Marie Gabriel Toulon, Paris, France, as-

signor to Products & Licensing Corporation, New York, N. Y., a corporation of Delaware 1 Application May 16, 1949, Serial No. 93,614 In France May 25, 1948 8 Claims.

The present invention relates to a new system for stabilizing the amplitude of an alternating voltage, ofiering the advantages of being, on the one hand, very powerful, and on the other hand, of assuring a very precise regulation. It applies more especially to the stabilization of the voltage at the terminals of an oscillating circuit connected with a driving circuit.

Voltage regulators usually employed heretofore have been, in general, of two kinds, those utilizing a rectifier, appropriately polarized to enable initiation of current flow when the voltage of the circuit surpassed a'certain limiting value, equal generally to that of the polarizing source, and

those utilizing a gas tube (such as a neon'tube) which fires at a predetermined threshold voltage. These devices are usually combined with a resistance, disposed in series with the circuit, and the current which flows in the resistance brings about a fall in voltage in that resistance, which opposes the accidental and undesired variations in voltage at the terminals of the circuit. However, voltage regulation systems of this character are neither powerful nor precise, since the resistance values have to have values selected to maintain satisfactory efiiciency, and the voltage which appears across the resistance does not precisely compensate for the variation which is to be annulled. Gaseous tubes present, besides, the disadvantage of being unstable in respect to firing voltage, of being dependant upon temperature conditions, of being subject to aging, and finally of passing a current which varies according to the voltage applied to the tube, which facts render the regulation obtainable imperfect.

All of these disadvantages are avoided by the present invention, which assures a flexible adjustment, and one which is automatic, very precise, very powerful, and positive in operation.

According to the invention, I dispose between the terminals of a circuit receiving an alternating voltage whose amplitude is subject to accidental variations which are to be regulated, an automatic restrictor, the functioning threshold of which is selected in such a way that it does not respond to these variations. I amplify the voltage to be regulated by means of an electronic tube circuit. I combine in the output circuit of the amplifier the amplified alternating voltage, with a rigorously constant voltage, such as that of a battery, in such a way as to produce a current which is a function of the relative values of the two voltages. I cause this current to react, by the means of an appropriate coupling, on the input circuit of the amplifier, in such a way as to lower the response threshold of the resistor which is disposed in the latter. I cause the latter, thereby, to begin to operate, in such a way as to reduce the accidental variations in voltage,

"which are found thereby to be limited at a practically constant level.

The invention comprises various specific embodiments. The restrictor in the input circuit may consist of a rectifier in series with a polarizing source, which may be a battery, which normally blocks the rectifier, and which is selected in such a way that it remains insensitive to a certain margin of increase of input signal. The means of comparison in the output circuit may likewise comprise a rectifier in series with a blocking battery. The latter is selected to have a value such that any increase in voltage above a desired value causes current flow through the rectifier. The current thus produced brings about, in combination with a circuit, having an appropriate time constant, a continuous slowly varying difference in potential, which is applied to the input restrictor, by the intermediary of a feedback circuit, preferably provided with means for blocking the input signal; this difierence in potential controls the voltage variation in the input circuit. It is introduced in series with the rectifier in the input circuit, in opposition to the blocking battery. Theoperating threshold of the rectifier is thus greatly lowered, and the current which it passes then brings about a fall in voltage in a resistance disposed in series with the input circuit, absorbing the accidental variation.

The invention is more especially interesting in the case of existing systems comprising amplifiers connected with oscillating circuits, in which case the present system can be applied to the existing amplifiers.

The invention will be better understood by reference to the accompanying drawings, where- 1n:

Figure 1 is a schematic circuit diagram, in accordance with the invention, wherein regulation is accomplished of voltage furnished by an oscillating circuit, an input restrictor and output regulator being employed, which are each of the biased rectifier type;

Figure 2 represents operating characteristics of the system of Figure 1, provided purely for purposes of simplifying the explanation of the operation of the system.

In Figure 1, I have shown at l2 the terminals of a conventional generator of alternating current, G, represented as an oscillating triode,

with a feed back circuit. It is assumed that the power furnished by it is to supply a load, which may be connected to terminals 3, 4, via an amplifying tube 5, having an anode supply 6, a grid I, an anode 8, a cathode 9, and a coil in in the anode circuit coupled to an oscillating circuit, across which are connected terminals 3, 4. The problem which the present invention proposes to solve is to stabilize in a very precise fashion, the amplitude of the alternating voltage at the terminals 3, 4.

This result is obtained by a feedback process. I connect in series between the terminal I and the grid I of the amplifiena resistance R. Terminal 2 is connected to thecathode 9. Connected from grid 1 to cathode. 9 is a rectifier I2, in series with a battery I3, and a resistance It shunted by a condenser I5. The battery I3 is poled to oppose the passage of current in the rectifier I2, its positive pole being connected to the cathodic terminal thereof. Across the oscillating circuit II, and hence across the terminals 3, 4, is a further rectifier I-6, inseries witha battery I7 and a resistance I8 shuntedby a condenser IS. The battery I! is poled insuch a way as to block or off-bias the rectifier I6. The voltage at the terminals of the condenser I9 is applied to condenser I via a coil 20, which passes the D.-C. component of any voltage present across condenser I9, without transmitting the alternating or signal component of that voltage. The condenser I5 thus acquires a voltage the polarity of which isindicated in Figure 1, and which is opposedto that of the battery I3.

Figure 2 represents, as a function of time, the voltages which appear in the different parts of the system of Figure l, and assists in facilitating understanding of the general operationof the system. It is to be understood that Figure 2 provides only an approximateillustration of this operation, and is only given here as exemplary, and to assist in comprehension of the disclosure. The first curve represents, as a function of time, the voltage which appears between terminals 22,

23', connected between grid I and cathode 9, and

which represents the input signal to the amplifier 5. The left half of curve 2-I corresponds to the voltage actually present at the terminals 22, 23. The right half, at 24 (above the dotted lines), cannot exist precisely because of the operation of the regulator system, i. e., is the voltage which would exist were the regulator system absent. The second curve, 25, shows the actual form of the voltage applied to the grid of tube 5, in consequence of the simultaneous intervention of the amplitude regulating device, and of the presence of the oscillating voltage provided by the generator G.

The third curve, 26, represents the voltage at the output terminals 3, 4, that is to say after amplification by the tube'5.

At the beginning of the operation, the condenser I5 is not charged. The generator G, beginning to oscillate, impresses an alternating volt- .age on the input terminals 22, 2-3 of the amplifier. tube 5.

It is assumed that this voltage increases progressively. If no other phenomenon existed the rectifier I6 would eventually pass current. This would produce peaks, as at 24, when the maxima of the curve 2| surpass the horizontal tory. According to the present invention,,I in-- crease enormously the sensitivity of th regulator, thanks to the feedback circuit, described hereinafter. I so select the coeflicient of amplification of the tube 5, the voltage of the bias battery I! and the voltage of the bias battery I3, that the rectifier I6 begins to pass current before the rectifier I2 does, and as soon as the maximum of the alternating voltage 26 appearing in the oscillating output circuit II becomes greater than the voltage of the bias battery I1 (represented in Figure 2 by the horizontal line V--V). At this voltage, the rectifier I6 begins to pass current, represented by the shaded portions 21, which brings about a relatively large fall in voltage across theresi'stance I8, and causes the condenser I9 to-charge.

I have represented, on the fourth line of Figure 2', the voltage 28 which appears across the condenser I2, as a function of time. As soon as the voltage 26 rises above the horizontal line V -V, a voltage 28 appears on'the condenser I9. This voltage is transmitted to the condenser I:5, which diminishes the effect of the bias voltage of battery I3 on the rectifier I2. In Figure 2, we have taken this effect intoaccount, by plotting the curve 28 against the line 22, which represents the voltage of battery I3. We construct thereby a curve 29 exactly like the curve 28, but inverted.

The voltage at the terminals 22; 23, is found to be limited to the shaded part situated below the curve 29. The voltage thereby obtained would correspond to that which would exist on the grid I of the tube 5, if no oscillating circuit existed in the circuit of the generator G, but the presence of this oscillating circuit has theeffect of rendering all the voltages sinusoidal. The rectifier I2 thus exercises only an attenuating efiect on the oscillating circuit, reducing the amplitude of the oscillations in the circuit G. Thevoltage 25, which is approximately a sinusoid, having the curve 29 as an envelope, represents approximately the voltage which is actually applied to the grid of tube 5. The voltage 25, which is zero when oscillator G commences operation, begins thus to increase until it attains the amplitude 30. Beginning with this moment the rectifier I6 begins to function, which induces, as illustrated at 3|, an abrupt reduction in amplitude. The amplified voltage at the output undergoes the same variations. As a result, during some alternations of voltage, for example those below lines 2-2 in Figure 2, the rectifier I6 no longer exercises its effect, because the voltage has not yet disappeared from the condenser I9. But after a few alternations, as at 21, when the voltage of the condenser I9 has been sufiiciently reduced, the rectifier I6 passes current again, causing again an increase of voltage at the terminals of the condenser I9. This eflects again a rapid reduction of amplitude, and the process continues in this manner. After a few oscillations, the si nal amplitude at the output terminals 3, 4' is maintained at an extremely precise value, because the slightest flow of current via rectifier I6 has the eifect of modifying in a very rapid manner the voltage of the condenser I9. We understand that the sensitivity of the circuit is considerably increased by the amplification of tube 5. The voltage at the terminals 22, 23 is found thereby to be stabilized, and tube 5 now only furnishes a continuously controlled power. The voltage ceases to increase at the terminals 3, 4 and is rigorously stabilized.

This stabilization is extremely precise by reason of the fact that the coeificient of amplification of the tube is generally very great. For example, the voltage of the battery i3 is of the order of 1 volt, and the voltage of the battery i1 is of the order of 500 volts. Suppose, for example, that the amplitude of the alternating voltage at terminals 3, 4, surpasses the voltage of the battery H, if only by 0.5 volt (for example, 1000 of its value), the voltage engendered on the resistance [3 is of the same order of greatness, or slightly less, say 0.4 volt; this voltage, in part transferred to the condenser I5 induces therein a slightly weaker voltage, but of the same order of magnitude, say 0.3. The amplitude of the voltage at 22, 23, which was 1 volt, is therefore reduced to l-0.3=0.7 volt. It thus appears that the power furnished by tube 5 is reduced to about 30% of its value. The regulating efiect is thus enormous. In actuality such large variations have no chance of being produced, even in pass" ing abruptly from operation with no output to full output, that is to say, the stabilization is extremely perfect. It would not have been the same with a regulator arranged in the conventional manner, because the variation of voltage at the input would have been only /1000 of its value instead of /1000.

While I have described and illustrated a specific form of the invention it will be clear that variations thereof may be resorted to without departing from the true scope of the invention as defined in the appended claims.

What I claim and desire to secure by Letters Patent of the United States is:

. 1. An amplitude regulator for periodic voltages, comprising, a source of oscillations, a vacuum tube amplifier having an input circuit and an output circuit, a voltage dropping resistance con nected in series between said source of oscillations and said input circuit, a biased rectifier connected across said output circuit, and means responsive to current flow in said rectifier for controlling voltage drop in said voltage dropping resistance.

2. An amplitude regulator for periodic voltages, comprising, a source of oscillations, a vacuum tube amplifier having an input circuit and an output circuit, a voltage dropping resistance connected in series between said source of oscillations and said input circuit, a rectifier biased in one polarity connected in series with a condenser across said output circuit, an oppositely biased rectifier connected in series with a condenser across said input circuit, means responsive to voltage across said first named condenser for reducing bias of said oppositely biased rectifier by charging said last named condenser, and means responsive to current flow in said oppositely biased rectifier for controlling voltage drop in said voltage dropping resistance.

3. An amplitude regulator for periodic voltages, comprising, a source of oscillations, a vacuum tube amplifier having a cathode, an anode, and a control electrode, a voltage dropping resistor, means connecting said source of oscillations in series with said voltage dropping resistor, means connecting said cathode and control electrode across said source of oscillations and said resistor connected in series, with said control electrode connected to a terminal of said resistor, a rectifier having an anodic terminal, a source of voltage, a condenser, means connecting said rectifier, said source of voltage and said condenser in series between said cathode and said control electrode, said anodic terminal being connected to said terminal of said resistor and with said source of voltage poled to bias said rectifier against current flow, an output circuit coupled to said amplifier, and means for controlling voltage across said condenser in response to voltage across said output circuit.

4. In a voltage regulator, a source of oscillations, an amplifier having an input circuit and an output circuit, a rectifier and means for providing a variable bias for said rectifier connected in series across said input circuit, whereby current fiow in said rectifier is responsive to said variable bias, and means responsive to voltage across said output circuit for determining said variable bias.

5. In a voltage regulator, a source of oscillations, an amplifier having an input circuit and an output circuit, a rectifier circuit having a fixed direct current bias and a variable direct current bias opposing said fixed direct current bias, said rectifier circuit connected in shunt to said input circuit, and means responsive to deviations from a predetermined value of voltage in said output circuit for varying said variable direct current bias.

6. In a voltage regulator, a source of oscillations, an amplifier having an input circuit and an output circuit, means coupling said input circuit to said source of oscillations a rectifier having a fixed D.-C. bias and a variable D.-C. bias opposing said fixed D.-C. bias, said rectifier connected shunt to said input circuit, a rectifier circuit coupled to said output circuit and comprising a source of bias voltage for preventing current flow in said rectifier circuit in response to voltage of less than a predetermined magnitude, and means responsive to said current flow for determining said variable D.-C. bias.

7. The combination in accordance with claim 6 wherein said means responsive to said current flow comprises a condenser connected in series with said rectifier and said source of bias voltage, a discharge resistance shunting said condenser, and means responsive to average voltage across said condenser for establishing said variable D.-C. bias.

8. An amplitude regulator for periodic voltages, comprising, a source of periodic voltages comprising an oscillating circuit, a rectifier shunting at least part of said oscillating circuit, means for biasing said rectifier against passage of current therethrough, said means for biasing comprising a source of constant direct current voltage and a source of variable direct current voltage opposing said constant direct current voltage, means for amplifying said periodic voltages to provide amplified signals, and means responsive to said amplified signals for controlling the magnitude of said variable direct current voltage.

PIERRE MARIE GABRIEL TOULON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date 1,931,866 Heising Oct. 24, 1933 2,079,444 Fyler May 4, 1937 2,397,337 Clough Mar. 26, 1946 2,472,301 Koch June '7, 1949 

